F7 Seasoned Floor Joists Print E-mail
F7 Seasoned Floor Joists
In general terms, there are four elements to a simple beam or joist situation:
  • The span between the two support points
  • The load to be supported by the beam or joist
  • The size or cross-section of the beam or joist
  • The grade of the beam or joist
These four elements are interdependent. For example - if the grade is increased then the size or cross-section of the beam or joist can be reduced.

There is more than one method of assigning an "F grade" to an individual piece of timber. (See: F Grades)

It should be noted that when individual pieces of timber have been assigned an "F grade", the species of timber doesn't matter. Even though some species of timber are inherently stronger than other species, each species will have been graded to the appropriate part of the appropriate grading rules to ensure that the individual pieces will have the properties of the assigned "F grade".

F7 is one of the most common grades of softwood used for joists in domestic construction.

Species available include Radiata pine, Slash pine, Cypress and Oregon.

Some species (Radiata pine and Slash pine) are available with preservative treatment. (See: Treated Timber)

Solid seasoned timber floor joists are an excellent and versatile choice of material for a wide range of flooring applications. F7 seasoned timber is available in long lengths - up to 6 m and in a range of sectional sizes up to 290 x 45 mm (300 x 50 mm Nominal).

Solid F7 seasoned timber is easily worked on site, connections are quickly made with standard carpentry tools and nails and there is a range of metal connectors well suited to the material.

Seasoned F7 Floor Joist Span Tables published in the Residential Timber Framed Construction Standard are for floor joists that support floor sheets only. When the floor joists support tongue and grooved 19 mm flooring the spanning capacity of the floor joist may increase.

Special span tables have been produced to take full advantage of the effect of tongue and grooved flooring.

Timber Information Bulletin 1: Seasoned Floor Joists
(PDF, 0.2 MB)
Australian Timber Importers Federation